This invention relates to an automobile bumper formed of a thermoplastic multicomponent resin composition.
Nowadays bumpers formed of synthetic resins are widely popular in automobiles. For example, thermosetting urethane resins are used for producing automobile bumpers by a reaction injection molding (RIM) method.
However, thermosetting urethane resins are generally weak in weather resistance so that the molded automobile bumpers need to be heavily painted or very carefully and frequently waxed. Besides, the molding operation suffers from a relatively large number of unacceptable products, and it is impossible to reuse the unaccepted bumpers as the molding material.
Also thermoplastic elastomers (TPE) comprised of propylene-ethylene block copolymer and EPDM rubber are used as injection molding materials for automobile bumpers. However, TPE bumpers are insufficient in impact resistance at low temperatures. In most cases these bumpers break by a 5 km/hr pendulum impact test at -30.degree. C. Therefore, TPE bumpers are practicable only in limited regions. Besides, TPE bumpers are relatively low in surface gloss and, hence, in commercial value. In painting TPE bumpers it is not easy to realize a desirably smooth and beautiful surface of the paint film.